Manuel Margot, CF
The power that Margot showed in April is still missing in June, but he's at least managed to bring his batting average up, and his on-base percentage along with it. While his .262/.333/.379 season line might not look like all that much, you have to remember that he's just 19 years old, or, about two-and-a-half years younger than your average position player spending their summer in the Low-A Sally. That player, by the way, is batting .260/.331/.379, right in line with Margot. When you consider that Margot, who has only played short-season ball before 2014, is keeping pace with your average Sally player, who very likely given their average age has either spent time in Low-A or in college previously, his production to this point becomes more encouraging.
In addition to him not showing much power yet because of his age, remember that's all of 170 pounds. As he fills out and adds muscle over the next couple of years, we might see him have a breakout in power. Not every prospect is going to pull a Xander Bogaerts when they're teenagers in the low minors, so we shouldn't judge them all on that kind of accelerated timetable.
Jamie Callahan, RHP
Speaking of youth and inexperience, Callahan has had a rough go of things lately. While his peripherals look solid enough for the most part, he's been getting hit far too often for his own good, allowing nearly 13 hits per nine innings, resulting in nearly two baserunners per inning when you account for his 4.5 walks per nine. He's keeping the ball on the ground instead of in the air, so opposing hitters can only be hitting the ball so hard and so square, but it seems like everything the opposition makes contact with is turning into a hit.
Whether that's all from poor luck, or it has to do with Callahan learning the ropes of full-season ball slower than you'd like, is unknown. It could safely be argued, though, that he needs to work on not only throwing more strikes, but also throwing more quality ones when he manages to do so. The walks are likely a byproduct of an approach that induces grounders, but too many baseballs are likely being left up just enough for opposing batters to put a charge behind their grounder and get it through an infield hole.
Myles Smith, RHP
Dating back to May 1, Myles Smith has walked 27 batters and struck out just 19 over 34-1/3 innings and nine starts. Just 58 percent of his pitches were strikes, and unlike with Callahan, you can't blame a focus on trying to induce grounders as the culprit. He's just been flat-out bad in his introduction to full-season ball, and little has improved with time.
Smith is also 22, so he doesn't have the age excuse of Callahan, but he is relatively new to pitching and was never considered a polished product before he was bumped to Low-A. Smith also threw just 10 innings for short-season teams in 2013 after he was drafted in the fourth round last summer, so try to remember that this was a tougher assignment than his age indicated.
With that being said, any frustrations or concerns with his performance to this point are understandable. Smith needs to show something in the second half before we start to worry that he'll be a 23-year-old college arm repeating the lowest level of full-season ball out there next year.